Garden Talk: August 13, 2009

From NGA Editors

Butterfly-Attracting, Disease-Resistant Phlox

Midsummer is tall phlox (Phlox paniculata and P. maculata) season in the perennial garden. Phlox is known for its beautiful flowers this time of year, but powdery mildew often ruins the show. There are disease-tolerant varieties of phlox available, but none are as attractive to butterflies as Jeana phlox (P. paniculata Jeana).

Jeana grows 3 to 4 feet tall and 2 feet wide. It produces clusters of small pink flowers by midsummer. The long-lasting, sterile flowers are butterfly magnets. If grown side by side with other phlox varieties, most of the butterflies alight on Jeana. The leaves are resistant to powdery mildew and, like all tall phlox, Jeana is hardy in USDA zones 3 to 9, growing best in full sun on well-drained soil.

Save the Ash Tree

There is a growing concern about native ash trees across the country. The emerald ash borer (EAB) insect has set up home in communities in the Midwest, Mid-Atlantic, Northeast, and Eastern Canada regions, killing tens of millions of ash trees and threatening to spread to other areas. This exotic pest has no known enemies and can kill an ash tree within a few years. While researchers scramble to come up with strategies to control this pest, scientists at the USDAs Rose Lake Plant Materials Center in Michigan have started a National Ash Tree Seed Collection Initiative. Their goal is to collect a diverse sampling from a wide variety of ash trees nationwide and use them to preserve the germplasm for future reintroductions of ash trees in case the tree goes the way of the American chestnut.
The Rose Lake Center staff are enlisting volunteers to help collect seed from around the country. The seed is sorted, classified, and x-rayed to determine viability. Viable seed is them stored at the Genetic Preservation Facility in Ft. Collins, Colorado.

Elderberry Pruning Trials

Elderberry bushes are gaining in popularity. This native shrub is easy to grow and is adapted to a wide range of climatic conditions, including wet areas. It features attractive white flowers and nutritious and delicious berries in summer. The shrub is also a favorite of birds and wildlife. However, until now no one knew the best way to prune the shrub for highest fruit production.

Researchers at the University of Missouri trialed four different pruning methods to determine which one favored the best elderberry production. From 2000 to 2006 researchers on two sites in southern Missouri grew Adams II, Bob Gordon, and Netzer elderberry varieties. Some bushes were pruned all the way back to the ground each year, some pruned back to the ground every other year (biannually), some selectively pruned to remove old wood, and some not pruned at all.

Researchers determined that for large-scale production of elderberries, pruning shrubs back to the ground each year worked the best. Although this technique yielded up to 20 percent less fruit than the other techniques, annual pruning resulted in high average yields, fewer disease problems, less loss to birds because they had difficulty landing on the more pliable young stems, and easier overall cultivation. It also reduced labor costs  an important consideration for large-scale growers. (Selective pruning requires that each shrub be hand pruned rather than whole rows being cut with a mower.) However, because higher overall yields were obtained with selective pruning -- removing old, non-bearing limbs annually and opening up the bush to new growth  this technique may be the best one for home gardeners looking to optimize production from few shrubs.

National Community Gardening Week

Secretary of Agriculture Tom Vilsack has named August 23-29, 2009, National Community Gardening Week. As an ongoing commitment to encourage community gardening, the USDA is installing Peoples Gardens at USDA facilities around the world. These community gardens are places people can grow their own food and donate extra to local food shelves. This summer the Peoples Garden at the USDA headquarters on the National Mall in Washington, DC, has donated more than 170 pounds of produce to The DC Central Kitchen. The DC Central Kitchen offers job training in culinary and food service skills to DC's homeless.

Across the country there are more than 1 million community gardens that produce on average about $500 worth of produce per garden each year. These gardens not only provide, fresh, healthy, locally raised food to the participants, they also become a hub of community-building activities. They beautify neighborhoods, become meeting places for residents, and help foster a sense of pride and belonging in the community.

For more information on National Community Gardening Week, go to: USDA

The National Gardening Association Web sites include information on the benefits of community gardening as well as helpful advice for gardeners. For more information, go to: garden.org and kidsgardening.org